Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
int n,m;
char a[100][100];
queue< pair<int,int> >q;
int d[4]={0,1,-1,0},c[4]={1,0,0,-1};
int dd[100][100];
void step(){
    while(!q.empty()){
        int xx1=q.front().first;
        int xx2=q.front().second;
        q.pop();
        for(int i=0;i<=3;i++){
            int x1=xx1+d[i];
            int x2=xx2+c[i];
            if((a[x1][x2]=='.')&&(dd[x1][x2]==0)){
                dd[x1][x2]=dd[xx1][xx2]+1;
                q.push(make_pair(x1,x2));
            }
        }    
    }
}
int main(){
    cin>>n>>m;
    int count =0;
    dd[1][1]=0;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            cin>>a[i][j];
            if(a[i][j]=='#'){
                count++;
            }
        }
    }
    q.push(make_pair(1,1));
    step();
    if(dd[n][m]==0)
	    cout<<-1;
	else
	    cout<<n*m-count-dd[n][m]-1;

}